High temperature protectional apparatus for engine emissions catalytic converter

ABSTRACT

The invention comprises a device to determine either that abnormally high concentrations of unburned combustibles (unburned hydrocarbons and carbon monoxide) are present in an engine exhaust stream or that the emissions control catalyst temperature has exceeded normal levels, and an apparatus which prevents the flow of unburned combustibles into the emissions control catalylst bed and activates an alarm to the engine operator upon such determination.

United States Patent 1191 Morgan et al.

1451 Jan. 21, 1975 154] HIGH TEMPERATURE PROTECTIONAL APPARATUS FOR ENGINE EMISSIONS CATALYTIC CONVERTER [75] Inventors: Charles R. Morgan, Wenonah;

Richard C. Murphey, Woodbury,

both of NJ.

[73] Assignee: Mobil Oil Corporation, New York,

[22] Filed: Apr. 17, 1973 21 Appl. No.: 351,925

[52] US Cl. 60/277, 23/288 F, 60/288, 340/227.1

[51] Int. Cl F01n 3/14 [58] Field of Search 60/277, 288; 23/288 F; 340/227 R, 227.1, 228 R; 337/401 [56] References Cited UNITED STATES PATENTS Raymond 60/277 3,214,246 10/1965 Ridgway 60/288 3,277,457 10/1966 Herman 340/227 R 3,367,175 2/1968 Morreal 1 337/401 3,594,750 7/1971 Mueller .t 340/227.l 3,738,108 6/1973 Goto (10/277 Primary ExaminerDouglas Hart Attorney, Agent, or FirmAndrew L. Gaboriault; Michael G. Gilman [57] ABSTRACT The invention comprises a device to determine either that abnormally high concentrations of unburned combustibles (unburned hydrocarbons and carbon monoxide) are present in an engine exhaust stream or that the emissions control catalyst temperature has ex ceeded normal levels, and an apparatus which prevents the flow of unburned combustibles into the emissions control catalylst bed and activates an alarm to the engine operator upon such determination.

3 Claims, 1 Drawing Figure HIGH TEMPERATURE PROTECTIONAL APPARATUS FOR ENGINE EMISSIONS CATALYTIC CONVERTER BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION The invention concerns the reduction of undesirable exhaust emissions from engines which produce power through the combustion of hydrocarbon fuel. More specifically the invention deals with the reduction of unburned hydrocarbons and carbon monoxide in the engine exhaust.

2. DESCRIPTION OF THE PRIOR ART Unburned hydrocarbon and carbon monoxide emissions are regarded by many as representing a substantial source of air pollution. Engine emissions are subject to photochemical reaction in the atmosphere producing what has been termed smog and which is considered an irritant of eye and respiratory system tissues. The carbon monoxide and unburned hydrocarbons present in engine exhaust are the result of incomplete combustion or oxidation of the hydrocarbon fuel. Complete oxidation would transform carbon monoxide to carbon dioxide and unburned hydrocarbons to carbon dioxide and water, probably in the form of steam due to the high combustion temperature. Neither carbon dioxide nor steam are considered harmful emissions.

Various means have been employed to reduce or eliminate carbon monoxide and unburned hydrocarbon emissions. One approach has been to pass the engine exhaust gases through a catalytic converter located in the engines exhaust system where the carbon monoxide and the hydrocarbons are oxidized, usually by the introduction of supplemental air, to carbon dioxide and water.

The amount of unburned hydrocarbon fuel and carbon monoxide present in an engines exhaust varies to a certain extent based on operating conditions, however it should not exceed about 8 percent by weight of the total exhaust gases. If this percentage is significantly increased due to an engine malfunction, the catalyst will experience a temperature excursion because of the highly exothermal nature of this oxidizing reaction and the large amounts of unburned fuel and carbon monoxide in contact with the catalyst. This dramatic temperature rise poses a threat not only to the catalyst, which is often sintered or melted to deactivation by such temperatures, but also to people or equipment near the catalytic converter.

Experiments indicate that if an automobile equipped with a typical emissions control catalytic converter traveling at miles per hour were to completely lose ignition, the temperatures in the catalytic converter will increase to more than 2,500F. (more than l,300F above normal operating temperatures) in the few seconds it takes the engine to coast to a stop. The dangers of an automobile catching fire due to such a temperature increase and/or otherwise being damaged are clear. Furthermore, even if the automobile or its occupants (the converters location in the exhaust system will place it under that portion of the automobile in which the operator and passengers sit in most automobile designs) are not harmed by such a temperature increase, the emissions control catalyst would be seriously damaged to the extent that its performance would be severely impaired.

This invention is not limited to use in conjunction with only reciprocating-piston internal combustion engines, or to engines which induce combustion electrically, but may be utilized with any engine which burns hydrocarbon fuel. However, for purpose of illustration, a spark ignition reciprocatingpiston internal combustion engine will be explained briefly to describe one of the adaptations of this invention. The following are malfunctions of such an engine which may produce abnormal amounts of carbon monoxide and unburned hydrocarbons in exhaust gases sufficient to give rise to the dramatic increase in emissions catalyst temperatures previously discussed:

1 A broken electrical ignition wire or an electical ignition wire with a connection which has become loose; (2) severely fouled spark plugs; (3) carburetor maladjustment or malfunction; (4) complete loss of ignition; (5) an obstructed air intake, such as due to a heavily fouled air filter; (6) a damaged cylinder; or (7) an ex-,

haust valve maladjustment or malfunction.

The reciprocating piston internal combustion engine operation with spark ignition wasoriginally proposed by Beau De Rochas and later developed by Otto in 1876(It is now commonly referred to as the Otto cycle and is found in most automobiles now in use. It may be briefly described as follows:

A piston slides back andforth in-a cylinder and transmits power to move the automobile, typically through a connecting rod and crank mechanism coupled with the drive shaft. Initially the piston slides so as to draw air and fuel, mixed to a given proportion in the carburetor into the cylinder of the engine. This is known as the intake stroke as the intake valve is open during this portion of the Otto cycle. Next the piston moves to compress the combustible mixture in the cylinder thus raising the temperature of the mixture in what is termed the compression stroke. Both the intake and exhaust valves are closed during this stroke. The air fuel mixture is then ignited through use of a spark plug whcih creates a spark due to a high voltage produced by the electrical ignition system. The ignition and subsequent burning of the hydrocarbon fuel raises the pressure of the gases causing the piston to move in what is termed the expansion or power stroke. The intake and exhaust valves are also closed during this stroke. Finally the exhaust valve opens and the piston moves in an exhaust stroke to sweep the products of combustion and any unoxidized hydrocarbons and carbon monoxide out of the cylinder and into the engines exhaust manifold. The manner in which the illustrative malfunctions of an internal combustion engine, listed earlier cause abnormally high concentrations of carbon monoxide and hydrocarbon emissions in the exhaust gases, may be explained with reference to this brief description of the Otto cycle.

If the air intake is obstructed or the carburetor does not mix the air and fuel in the proper ratio, the resultant misture may be too rich (insufficient amount of air) to allow for complete combustion during the power stroke. The unburned hydrocarbons and partially oxidized carbon in the form of carbon monoxide then pass into the exhaust system during the exhaust stroke.

In a similar manner, total loss of ignition or a partial loss due to a broken or loose ignition wire or severely fouled spark plugs, will result in total or partial incomplete combustion in those cylinders affected. Upon total loss of ignition, none of the air and fuel is ignited during the power stroke and the entire air fuel mixture passes into the exhaust system during the exhaust stroke.

If the exhaust valve does not seat into the cylinder properly during the compression or power strokes, unburned fuel and carbon monoxide will be passed into the exhaust system.

Each of these malfunctions will produce an abnormal amount of hydrocarbons and carbon monoxide in the exhaust system, which upon entering a catalytic converter catalyst bed, may produce significantly increased catalyst temperatures. Again it is emphasized that the examples given which might produce high amounts of unburned fuel and carbon monoxide are cited only to illustrate the need for a device to protect the catalyst from the dramatic temperature increase that they produce. Applicants invention will protect the emissions catalyst from excessive temperatures regardless of the reason for excessive amounts of hydrocarbons and carbon monoxide being present in the exhaust gases. Moreover, it is not limited to reciprocating-piston type internal combustion engines with spark ignition. It may be used in conjunction with any engine which produces power by burning hydrocarbon fuels and which has a catalytic emissions converter and thus, can be utilized with turbine, diesel, rotary and reciprocating-piston internal combustion engines in addition to external combustion engines.

It is a primary objective of this invention to prevent the dramatic temperature increase of emissions catalyst due to abnormally high amounts of incompletely burned combustibles in an engines exhaust gases. A further objective is to determine when the emissions catalyst temperature is increasing above normal levels. An additional objective is to give an indication to the engine operator when the emissions catalyst has experienced excessive temperatures. (Indications of these conditions will serve to notify the operator that he should examine the engine and catalytic converter as their operation is not normal.) Another primary objective of this invention is to prevent abnormally high concentrations of incompletely burned combustibles from entering the catalytic converter thus, preventing excessive catalyst temperatures. Other and additional objects of this invention will become apparent from a consideration of this entire specification including the claims and drawings.

The invention comprises a means to determine that abnormally high concentrations of incompletely burned combustibles are present in an engine exhaust stream and to prevent the flow of incompletely burned combustibles into an emissions catalyst bed and/or alert the engine operator upon such determination. Abnormally high concentrations of incompletely burned combustibles may be measured indirectly by measuring the conditions caused by the high amounts of combustibles (increased catalysts bed temperatures).

SUMMARY OF THE INVENTION The invention may be embodied by means to determine excessive catalyst temperature through utilization of one or more electrical conductors of appropriate melting point. The conductors are inserted in the catalyst bed so that they extend through the bed. The ends of the conductor protruding from the catalyst bed are connected to an electrical sensing device which determines when a conductor has melted. The conductors are selected to melt at temperatures between normal catalyst operating temperatures and the temperatures at which the catalyst will be severely damaged. Should loss of ignition or other operational upset occur, the temperature of the emissions control catalyst bed will rise, as previously discussed, melting one or more conductors. The electrical sensing device which determines when a conductor has melted is utilized to initiate operation of a device to prevent the further passage of exhaust gases containing abnormally high concentrations of combustibles from entering the catalytic converter and/or to alert the operator. The melting of a conductor, which has a melting temperature at or near the level at which the catalyst is severely damaged, could also serve to indicate that the catalyst should be replaced. Once a high level of incompletely burned combustibles is detected, the invention as previously discussed, provides for means to prevent the contact of such unburned fuel and air with the emissions catalyst. Two means include a shut-off valve located at the carburetor or a vent line from the engine inlet manifold.

Other means which might be. utilized in conjunction with the previously described methods for determining abnormal engine operation to protect the catalyst include: providing a bypass around the catalyst bed,

water injection into the exhaust stream or shifting the engine drive into neutral.

Invention is not here claimed in the general use of a melting conductor to indicate temperature, and/or the various control valving arrangements which would be recognized to take advantage of the various information obtained by such means. Rather invention isclaimed in the entire system described in combination to sense an upset in the engine and/or exhaust converter operation and to take corrective and/or information action as a result of that sense.

BRIEF DESCRIPTION OF THE DRAWINGS The figure represents a schematic representation of an emissions control catalytic converter equipped according to this invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS The figure illustrates an emissions converter catalyst bed 12, housed in a suitable container 14, having an inlet 16 and an outlet 18. Electrically conductive materials may be inserted in the bed 12 and through the container 14. Electrical connections 24 are shown joined to the electrically conductive materials 20. When the termperature abnormally increases and therefore the electrical conductive material 20 melts, the circuit made up of the electrically conductive material 20, the electrical connections 24 and the electrical sensing device 22 is broken, an electrical current may be sent through an electrically conductive wire 48 to an indicator light and/or an electrical solenoid operated bypass valve 40, which forces the exhaust gases through a bypass line 44 and prevents their entry into inlet 18. The preferred melting point temperature range of electrical conductive materials 20 is I,600F to 2,300F. 1,800F indicates an operating malfunction. Temperatures above 2,300F indicate the catalytic converter catalyst 12 may be somewhat damaged. Melting of the catalyst will typically occur at about 2,5()0F to 2,600F.

The electrical circuit shown in the figure may be powered by a conventional power source 8.

The following examples are illustrative of this invention without being limiting thereon.

EXAMPLE 1 A standard platinum monolithic converter (PTX-S) was installed in the exhaust system of an internal combustion engine attached to a dynamometer. The engine was accelerated to a speed equivalent to a road speed of 30 miles per hour, and the ignition was cut off. The engine required approximately 215 revolutions during an elapsed time of 16 seconds to coast to a stop. During this time unburned air and fuel continued to enter the converter. The resultant oxidation increased the temperature of the catalyst and its monolithic support structure by more than l,400F. The catalyst was severely damaged by this extreme temperature. Approximately one-half of the catalyst and its support was melted by the heat produced by the exothermic oxidation reaction.

EXAMPLE 2 A PTX-S converter was installed in the exhaust system of an internal combustion engine attached to a dynamometer. The engine was accelerated to a speed equivalent to a road speed of 30 miles per hour and the ignition cut off. Simultaneous to the loss of ignition, a shut-off valve was closed in the carburetor and the inlet manifold was vented to the atmosphere. The catalyst temperature rose 550F. This temperature increase did not impair the catalysts performance or damage the catalyst support structure.

EXAMPLE 3 A 24 gauge nichrome V wire along with several thermocouples were inserted in the catalyst bed of a PTX-S converter. The external leads of the nichrome wire were connected to a continuous recorder which was used to sense the electrical continuity in the wire. The PTX-5 converter was tested on an engine dynamometer facility. When the engine ignition was shut off at an equivalent road speed of 30 MPH, catalyst temperatures in excess of 2,000F were measured as the engine coasted to a stop. At the same time the recorder indicated a loss of continuity through the nichrome wirc thus showing the wire had melted.

EXAMPLE 4 Measured amounts of C H hydrocarbon (dry basis) were passed through a PTX-S catalyst and the corre- I sponding increase in temperature of the catalyst recorded. The maximum temperature rise was found to be 93F per ppm of C hydrocarbon fuel. Therefore, 1.2 percent of C hydrocarbon fuel oxidized in the catalytic converter can actually cause melting of the catalyst support structure.

What is claimed is:

1. In an .engine assembly comprising: an engine; means for producing a combustible mixture of hydrocarbon fuel and air; means for burning said fuel and air to produce exhaust gases containing a varying proportion of combustible components; and means for controlling the quality of said exhaust gases including catalytic emissions control converter means, the improvement which comprises:

means for detection of an abnormally high concentration of combustibles in said exhaust gases; and

means operative in response to said detection indicating to the engine operator that a malfunction has occurred, said detection means comprising at least two electrical conductors in intimate association with said catalytic converter means, the first of said conductors having a melting point of about- 

1. In an engine assembly comprising: an engine; means for producing a combustible mixture of hydrocarbon fuel and air; means for burning said fuel and air to produce exhaust gases containing a varying proportion of combustible components; and means for controlling the quality of said exhaust gases including catalytic emissions control converter means, the improvement which comprises: means for detection of an abnormally high concentration of combustibles in said exhaust gases; and means operative in response to said detection indicating to the engine operator that a malfunction has occurred, said detection means comprising at least two electrical conductors in intimate association with said catalytic converter means, the first of said conductors having a melting point of about 1,800*F, melting indicating an operating malfunction, and the second of said conductors having a melting point of about 2,300*F, melting indicating catalyst damage.
 2. An improved engine assembly as claimed in claim 1, wherein said improvement further comprises means operative in response to said detection for reducing the flow of combustibles into said converter.
 3. An improved engine assembly as claimed in claim 2 wherein said means for reducing the flow of combustibles into said converter comprises a bypass around said converter through which said exhaust gases are passed. 